We quantified the abundance, species richness and species composition of three size classes of native woody plants before and a decade after mammal eradication in the Karori Wildlife Sanctuary. Inventories were made in two large plots, one of whichwas located in introduced pine forest and the other was located in an area free frompines. Results were used to evaluate changes in forest structure following mammalexclusion. Smaller tree size classes increased in abundance through time in bothplots. After controlling for the effect of plant abundances on estimates of speciesrichness, few differences in species richness were observed between plots or sampling times. However, strong differences in species composition were observed. Different suites of tree species inhabited each plot. Nevertheless, species composition changed in similar ways in both plots through time. Overall results indicate that in the decade following mammal exclusion at the Karori Wildlife Sanctuary, 1) seedling abundances increased markedly, 2) species richness remained largely unchanged, and 3) species composition changed markedly through time, but in similar ways in both plots. Results indicate that complex successional changes have occurred in the Karori Wildlife Sanctuary since mammal eradication.